If you get DNS servers from RA and from DHCP, throw them all in the candidate DNS server list. Unless something is
broken, any one of them should work and provide the same answers as the others.
You can't get NTP from SLAAC/RA, so, no conflict there. If the router and dhcp server administrators can't agree on
the DNS search list, then, you're going to have some problems no matter what protocol you use, so, I really think
this is a tempest in a teacup.